The present invention relates to implantable medical devices, particularly, to a percutaneously or minimally invasive heart valve, a delivery system and a method of use.
In recent years, the replacement of diseased or damaged cardiac valves by an artificial valve inserted either percutaneously or by a minimal invasive technique, has become standard for both high risk and non-operable patients. However, both the implantation procedure and the available valve prostheses have some limitations. Such limitations include the fact that hearts in general and diseased heart valves in particular vary widely in size, and finding an optimal valve prosthesis to provide a good fit for a specific diseased valve is a challenging task. Finding an appropriate fit is particularly problematic due to the relatively low accuracy of imaging tools, the large variation in the morphology and tissue properties of diseased valves, and the limited choice of available valve prostheses.
Artificial valves with dimensions providing a non-optimal fit to a specific patient's anatomy may cause clinical complications. For example, implantation of a too small prosthesis may result in paravalvular leak and valve embolization. Implantation of a too large prosthesis for a given diseased valve may cause arrhythmia due to compression on the conduction system, which may cause damage resulting in the patient requiring a pace-maker. In extreme conditions aortic valve replacement using a too large prosthesis can result in aortic annulus rupture.
Currently available prosthetic valves are designed to fit to a native valve having a specific diameter. The cardiac surgeon is required to measure the diseased native valve and to implant a suitably sized prosthetic. However, due to the limitation in measuring and misjudgments, in many cases the valve implanted is not the correct size. If the prosthetic valve is too large and not fully opened, the valve leaflets may include excess material which may result in a shortened life expectancy of the valve. Sometimes an expanded prosthetic valve may stretch the native valve, putting the patient at risk, due to electrophysiological complications and/or aortic root rupture. These complications are very serious and may be dangerous.
Where the prosthetic valve is undersized and is too small for the native valve, it puts the patient at risk of para-valvular leaks, displacement of the implanted valve and over expansion of the prosthetic valve beyond its designed diameter. Such problems may shorten the life expectancy of the valve or compromise its functionality, and puts the patient at risk.
In addition to the inherent problems of valves of the wrong size, the minimally invasive (MIS) implantation procedure as currently practiced has various disadvantages and risks for the patient.
During the implantation, the blood flow is partially or totally blocked by the expanding prosthesis. This requires the surgeons to expedite the prosthesis expansion step which increases the risk of mis-positioning the valve. Sometimes, surgeons use a rapid pacing procedure in order to decrease blood pressure however this may interfere with the accurate positioning of the prosthesis.
These complications increase the stress level of the surgeon and his teams and puts the patient at risk, and the success of the implantation may be compromised.